Baking lightmap with transparency shaders

Inside Unity 4, I had scene with the room, which had roof with transparency texture. I had directional light on top of the room.After baking, the light properly took transparency texture into account, and fall into the room. Without transparency, no light could pass, and room stayed black.


In Unity 5, I can't get it working. Sky abmient light passes through geometry, nothing helps. Even making material 2 sided. If I remove that light completely, and add just directional/spot/area/point light, it lights the room ins the same manner, i.e ignores geometry and transparency texture, acting as walls are 'transparent'. What is going on? No matter what I do, I can not replicate simple setup setup from Unity 4. I am the only one here with such problems, maybe I am missing something important?

Now I just tried simple test scene. Cube inside cube. That other 'inside' cube still gets litten afet lightmap. Why?

 

Finally, nailed it down. For some reason, after update from Unity 4 project, all my meshes had shadow casting set to OFF. Made it 2 sided, works as expected.